1. Field of the Invention
This invention pertains generally to electric motors. More specifically, this invention pertains to an electric motor that is adapted to be coupled to a liquid pump and that prevents liquid seepage from the pump from reaching the motor's stator.
2. General Background
Liquid pumps, such as those used in appliances, are typically coupled to and driven by electric motors. Liquid seepage from such a pump that migrates toward an adjacent electric motor can negatively impact the efficient operation of such an electric motor. For this reason, the electric motor and pump are typically oriented relative to each other in a manner such that the electric motor is not directly beneath the pump. In some cases, design constraints require the electric motor and pump to be positioned side-by-side. While positioning the electric motor to the side, rather than beneath the pump, inhibits seepage into the motor, liquid seepage from the pump bearings still may travel along the rotor shaft to be drawn into the stator.
In view of this concern, it is known to provide an electric motor with a liquid drainage cavity that is specifically configured to prevent liquid that has seeped past the rotor shaft bearing of the pump from being drawn by capillary action into the stator of the electric motor. The cavity is typically formed in the interface plate of the electric motor and encircles the rotor shaft in a manner providing an annular void around a portion of the shaft. The cavity thereby provides a place for seeped liquid to migrate and prevents capillary action from drawing the liquid into the stator, which would likely occur if there was little space around the shaft. Assuming the liquid seepage is slight, the cavity can serve as a reservoir for such liquid and thereby prevent the liquid from migrating into the stator. However, it is also known to provide the interface plate with a drainage passageway extending down from the cavity in an effort to drain liquid from the cavity so as to prevent the cavity from filling with liquid. Nonetheless, liquid draining from such a drainage passageway can create a partial vacuum in cavity which can inhibit further drainage of liquid from the cavity. Additionally, liquid draining from such a drainage passageway tends to collect on the bottom of the interface plate and run along bottom of the stator, where it can negatively impact the efficient operation of the electric motor.